I trashed the original with the question but: Sil phos is a
copper- silver - phosphorus brazing alloy family that is used
for copper brazing primarily. They are self fluxing and very
fluid. Thery don’t make a good collor match but they are strong
on copper. They can be used on brasses but are not always good
since they don’t all form as strong a joint on some of the opther
copper alloys. They are available from about 5 percent silver to
about 15 percent silver. Joining metals with a filler metal that
melts lower than the base metal and over I think its 800 degrees
F officially but about 1000 F degrees is a reasonable dividing
point. The common tin -lead etc solders melt below this and are
solders. Therefore all jewelry type work is Brazing not really
soldering in a technical sense. Jesse

Sil/Phos is a 15% silver phosporus brazing. It is used for
Refrigerant lines. The copper lines have to be heated to nearly
red hot to braze with sil/phos. I don’t think it would have any
Jewelry applications. Also when used with copper it is self
fluxing and can be used to fill gaps .

In jewelry work the quanities of gas used and the smallness of
the work are more forgiving than larger jobs with respect to
safety.